Methods and systems of deploying and retrieving streamer cleaning devices

ABSTRACT

Deploying and retrieving streamer cleaning devices. At least some of the example embodiments are methods including transferring a streamer cleaning device to a geophysical sensor streamer. The transferring may include towing the geophysical sensor streamer through water while the geophysical sensor streamer submerged, towing a tow fish through water by way of an umbilical (the streamer cleaning device coupled within a payload area of the tow fish during the towing of the tow fish through the water), landing the tow fish on the geophysical sensor streamer and thereby abutting the streamer cleaning device against the geophysical sensor streamer, closing the streamer cleaning device around the geophysical sensor streamer, releasing the streamer cleaning device from the payload area, and separating the tow fish from streamer cleaning device and the geophysical sensor streamer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 62/462,961 filed Feb. 24, 2017 titled “Streamer Cleaner UnitDeployment,” which provisional application is incorporated by referenceherein as if reproduced in full below.

BACKGROUND

Geophysical surveying (e.g., seismic, electromagnetic) is a techniquewhere two- or three-dimensional “pictures” of the state of anunderground formation are taken. Geophysical surveying takes place notonly on land, but also in marine environments (e.g., oceans, largelakes). Marine geophysical surveying systems frequently use a pluralityof geophysical streamers comprising sensors to detect energy emitted byone or more sources after the energy interacts with undergroundformations below the water bottom. For example, seismic streamers mayinclude sensors for detecting seismic signals reflected from thesubterranean formations.

Any object disposed in water in a marine environment is subject orsusceptible to marine growth (e.g., barnacles), particularly in tropicalwaters. To maintain equipment disposed in water, it may be advantageousto periodically clean the equipment. For example, to maintain the sensorstreamers, a streamer cleaning device may be used. Any apparatus ormethod that makes deploying and/or retrieving a streamer cleaning devicefaster, cheaper, and/or less dangerous may provide a competitiveadvantage in the marketplace.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of example embodiments, reference will now bemade to the accompanying drawings. It is noted that the various views ofthe accompanying drawings are not necessarily to scale.

FIG. 1 shows an overhead view of a marine geophysical survey system inaccordance with at least some embodiments;

FIG. 2 shows a side-elevation view of a marine geophysical survey systemin accordance with at least some embodiments;

FIG. 3 shows a side-elevation view of a marine geophysical survey systemin accordance with at least some embodiments;

FIG. 4 shows a side-elevation view of a marine geophysical survey systemin accordance with at least some embodiments;

FIG. 5 shows a side-elevation view of a marine geophysical survey systemin accordance with at least some embodiments;

FIG. 6 shows a side-elevation view of a marine geophysical survey systemin accordance with at least some embodiments;

FIG. 7 shows a side-elevation view of a marine geophysical survey systemin accordance with at least some embodiments;

FIG. 8 shows a side-elevation view of a marine geophysical survey systemin accordance with at least some embodiments;

FIG. 9 shows a perspective view of streamer cleaning device inaccordance with at least some embodiments;

FIG. 10 shows an elevation view of a streamer cleaning device in aclosed orientation around a sensor streamer in accordance with at leastsome embodiments;

FIG. 11 shows an elevation view of a streamer cleaning device in an openorientation in accordance with at least some embodiments;

FIG. 12 shows a perspective view of a tow fish in accordance with atleast some embodiments;

FIG. 13 shows a perspective view of a tow fish coupled to a streamercleaning device in accordance with at least some embodiments;

FIG. 14 shows a bottom view of the tow fish in accordance with exampleembodiments;

FIG. 15 shows an electrical block diagram of a control system inaccordance with example embodiments;

FIG. 16 shows a side-elevation view of a deployment and retrieval methodin accordance with at least some embodiments;

FIG. 17 illustrates a deployment method in accordance with at least someembodiments; and

FIG. 18 illustrates a retrieval method in accordance with at least someembodiments.

NOTATION AND NOMENCLATURE

Various terms are used to refer to particular system components.Different companies may refer to a component by different names—thisdocument does not intend to distinguish between components that differin name but not function. In the following discussion and in the claims,the terms “including” and “comprising” are used in an open-endedfashion, and thus should be interpreted to mean “including, but notlimited to . . . .” Also, the term “couple” or “couples” is intended tomean either an indirect or direct connection. Thus, if a first devicecouples to a second device, that connection may be through a directconnection or through an indirect connection via other devices andconnections.

“Cable” shall mean a flexible, axial load carrying member that alsocomprises electrical conductors and/or optical conductors for carryingelectrical power and/or signals between components.

“Rope” shall mean a flexible, axial load carrying member that does notinclude electrical and/or optical conductors. Such a rope may be madefrom fiber, steel, other high strength material, chain, or combinationsof such materials.

“Line” shall mean either a rope or a cable.

“Proximal” and “distal” shall be in reference to tow direction of ageophysical sensor streamer and measured along the geophysical sensorstreamer. Thus a proximal end of geophysical sensor streamer is closerto a tow vessel than a distal end of the geophysical sensor streamer.Likewise, a proximal portion of a geophysical sensor streamer is closerto the tow vessel than a distal portion.

“Crab” or “crabbing”, with respect to a tow fish, shall mean moving thetow fish axially along a sensor streamer where at least some of theforce to move the tow fish is provided by the tow fish itself (e.g., byoperation of a traction belt).

“Releasably couple” in relation to two objects shall mean the firstobject is selectively uncoupled from the second object without cutting,breaking, destroying, or otherwise rendering either the first object orthe second object unusable.

When a device or system is said to have a first orientation and a secondorientation, the orientations are not simultaneously achievable orsimultaneously present.

DETAILED DESCRIPTION

The following discussion is directed to various embodiments of theinvention. Although one or more of these embodiments may be preferred,the embodiments disclosed should not be interpreted, or otherwise used,as limiting the scope of the disclosure, including the claims. Inaddition, one skilled in the art will understand that the followingdescription has broad application, and the discussion of any embodimentis meant only to be exemplary of that embodiment, and not intended tointimate that the scope of the disclosure, including the claims, islimited to that embodiment.

Various embodiments are directed to deploying a streamer cleaning deviceonto a geophysical sensor streamer, and later and retrieving thestreamer cleaning device from the geophysical sensor streamer. Inparticular, various embodiments are directed to a tow fish that includesa payload area configured to releasably couple to a streamer cleaningdevice. The tow fish is towed by a surface vessel, and remotelycontrolled from a surface vessel (the towing and controlling need not bethe same vessel), such that the tow fish is maneuvered to couple thestreamer cleaning device to a geophysical sensor streamer. Similarly,after the streamer cleaning device has moved some distance along thelength of the geophysical sensor streamer, the tow fish is again towedby the surface vessel (and remotely controlled from a surface vessel)such that the tow fish is maneuvered to retrieve the streamer cleaningdevice from the geophysical sensor streamer. The description turns firstto an example geophysical survey system to orient the reader.

FIG. 1 shows an overhead view of a marine geophysical survey system 100(hereafter just survey system 100) in accordance with at least someembodiments. In particular, FIG. 1 shows a tow or survey vessel 102having onboard equipment, herein referred to collectively as recordingsystem 104, such as navigation, energy source control, and datarecording and processing equipment. Survey vessel 102 is configured totow one or more geophysical sensor streamers (hereafter just “sensorstreamers” or just “streamers”) 106A-F through the water. While FIG. 1illustratively shows six sensor streamers, any number of sensorstreamers may be used.

The sensor streamers 106A-F are coupled to towing equipment thatmaintains the sensor streamers 106A-F at selected lateral positions withrespect to each other and with respect to the survey vessel 102. Thetowing equipment may comprise two paravane tow lines 108A and 108B eachcoupled to the vessel 102 by way of winches 110A and 110B, respectively.The second end of paravane tow line 108A is coupled to a paravane 112,and the second end of paravane tow line 108B is coupled to paravane 114.The paravanes 112 and 114 are configured to provide a lateral forcecomponent to the various elements of the survey system when theparavanes are towed in the water. The combined lateral forces of theparavanes 112 and 114 separate the paravanes from each other until theparavanes put one or more spreader lines 116, coupled between theparavanes 112 and 114, into tension.

The sensor streamers 106A-F are each coupled, at the ends nearest thesurvey vessel 102 (i.e., the “proximal” or “forward” ends), to arespective lead-in cable termination 118A-F. The lead-in cableterminations 118A-F are coupled to or associated with the spreader lines116 so as to control the lateral positions of the sensor streamers106A-F with respect to each other and with respect to the vessel 102.Electrical and/or optical connections between the appropriate componentsin the recording system 104 and the sensors in the sensor streamers106A-F (e.g., sensor 128 in geophysical streamer 106A, discussed morebelow) may be made using inner lead-in cables 120A-F, respectively.

Each sensor streamer 106A-F can be conceptually divided into an activesection and a tail section with a tail buoy. Thus, the sensor streamers106A-F comprise active sections 122A-F, tail sections 124A-F, and tailbuoys 126A-F. There may, in fact, be multiple active sections in eachindividual sensor streamer. Referring to sensor streamer 106A asrepresentative of all the sensor streamers, active section 122Acomprises a plurality of sensors (e.g., sensor 128) spaced along theactive section 122A. Each example sensor 128 may be a seismic sensor(e.g., hydrophones, geophones), an electromagnetic sensor, or groups ofseismic and electromagnetic sensors.

In order to control depth of the active sections, and in some cases tocontrol lateral spacing between the sensor streamers, the active sectionof each sensor streamer may be associated with a plurality of streamerpositioning devices periodically spaced along the active section. Againreferring to sensor streamer 106A as representative, the active section122A of sensor streamer 106A may be associated with streamer positioningdevice 130 coupled near the proximal end of the active section 122A. Insome cases, the streamer positioning device 130 may provide only depthcontrol, as the lateral spacing of the sensor streamers near theproximal ends may be adequately controlled by the spreader cable 116.Further, representative active section 122A of sensor streamer 106A maybe associated with streamer positioning device 132, shown coupledfurther from the proximal ends near the distal end of the active section122A. The streamer positioning device 132 may provide only depthcontrol, only lateral control, or both. While FIG. 1 shows only two ofstreamer positioning devices 130 and 132 associated with active section122A of sensor streamer 106A, in practice each active section may havemany streamer positioning devices periodically spaced along the entirelength the active section (e.g., every 200 to 400 meters).

The active sections 122A-F may be referred to as “active” because duringa geophysical survey the sensors (e.g., sensor 128 associated withactive section 122A) may be used to gather data (e.g., seismic readings,electromagnetic readings), and more particularly during towing of thesensor streamers 106A-F. In practice, each active section 122A-F may bemade of a plurality of active segments coupled end-to-end by way ofcouplers. The active segments that make up the active sections, as wellas the couplers within the active sections, are not explicitly shown soas not to unduly complicate the figure. Further in practice, the lengthsof the active sections 122A-F may be from a few thousands meters to10,000 meters or more.

The sensor streamers 106A-F are also associated with tail sections124A-F, respectively. Again referring to sensor streamer 106A asrepresentative, the active section 122A defines a distal end 134. Theproximal end 136 of tail section 124A couples to the distal end 134 ofactive section 122A, such as by way of couplers 138. Representative tailsection 124A also defines a distal end 139, to which tail buoy 126A iscoupled. Representative tail section 124A thus couples the distal end134 of the active section 122A to the tail buoy 126A. The tail section124A and tail buoy 126A may serve many functions, such as marking theend of the sensor streamer in the water, providing support for thedistal end 134 of the active section 122A, and in some cases the tailbuoy 126A may have steering capabilities (which steering capabilitiesmay help placement of the active section 122A).

Still referring to FIG. 1, a chase or workboat 140 towing a tow fish 142via an umbilical 144 suspended from a derrick 146 may be used to deploya streamer cleaning device (not specifically shown) to a sensorstreamer. In the example of FIG. 1, the workboat 140 and tow fish 142are shown in operational relationship to sensor streamer 106E; however,the workboat 140 and tow fish 142 may transfer the streamer cleaningdevice to any of the example sensor streamers 106A-F. It is noted thatthe various objects shown in the overhead view of FIG. 1 are notnecessarily to scale; rather, the overhead view of FIG. 1 is designed toorient the reader to overall survey system 100.

FIG. 2 shows a side elevation view of survey system 100. In particular,FIG. 2 shows the survey vessel 102 towing sensor streamer 106 along apath of travel 200 within water body 201, such as sea water. In FIG. 2,for ease of illustration, only a single sensor streamer 106 is shown,but the sensor streamer 106 of FIG. 2 is representative of any of thesensor streamers 106A-F of FIG. 1. Also visible in FIG. 2 is innerlead-in cable 120 coupled to the active section 122, with active section122 including example sensors 128. Coupled on the distal end of theactive section 122 is the tail section 124, and coupled on the distalend of the tail section 124 is tail buoy 126. Example sensor streamer106 may be towed at a depth D beneath the surface of the water. Thetowing depth D is selected based on a variety of factors, such as theburial depth of a hydrocarbon reservoir and notch frequency in thegathered data, where the notch frequency is created by signals reflectedfrom the surface of the water incident upon the active section 122(i.e., surface ghosts). In some cases, the depth D may be about 20meters, but other depths are possible.

Any object disposed in water in a marine environment is subject orsusceptible to marine growth (e.g., barnacles). Marine growth is lesspronounced in cold water environments (e.g., the North Sea) and morepronounced in warm water environments, such as tropical waters. Themarine growth not only increases the towing force needed to pull thesensor streamers through the water, but also contributes to mechanicalnoise that adversely affects some seismic surveys. In order to reduce orremove the marine growth, periodically a streamer cleaning device isdeployed onto the sensor streamer. The streamer cleaning device movesalong the sensor streamer, physically removing marine growth andotherwise cleaning the sensor streamer. In related-art systems,deploying the streamer cleaning device involves raising the sensorstreamer to the surface using a work boat and attaching streamercleaning device. Thereafter, the sensor streamer is again submerged andthe geophysical survey can continue as the streamer cleaning devicemoves along the sensor streamer. Once the streamer cleaning devicereaches the distal end of the sensor streamer in the related art, thesensor streamer is again raised to the surface, and the cleaning deviceis removed. During periods of time when the sensor streamer is at thesurface, no geophysical surveying may take place, or at least no datacan be gathered from the sensor streamer at the surface.

In accordance with example embodiments of the invention, the streamercleaning device is deployed onto a sensor streamer, and later retrievedfrom the sensor streamer, while the sensor streamer is submerged,moving, and possibly recording data as part of a geophysical survey. Thespecification now turns to an explanation of deploying and retrievingthe streamer cleaning device in example systems. Referring again to thedrawings, FIG. 2 shows workboat 140 with tow fish 142 suspended from thederrick 146 (i.e., the tow fish 142 has yet to be placed in the water).In example embodiments, deploying the streamer cleaning device takesplace at the lead or proximal end of the sensor streamer 106. As thesurvey vessel 102 continues to tow the sensor streamer 106 along thepath of travel 200, the workboat 140 locates (in a macro sense) theproximal end of the sensor streamer 106 based on the location of thelead buoy 202. Once the workboat 140 is in the desired location relativeto the lead buoy 202 (and therefore over the proximal end of thegeophysical streamer 106), then the next phase of deployment begins.

FIG. 3 shows a side elevation view similar to FIG. 2. In the situationshown in FIG. 3, the workboat 140 has deployed the tow fish 142(including the streamer cleaning device 300 held within a payload area)into the water by paying out a length of the umbilical 144. Because thesurvey vessel 102 continues to tow the sensor streamer 106, the workboat140 likewise continues to move in a direction parallel to the surveyvessel 102 to maintain a desired relationship to the lead buoy 202 andthus the proximal end of the sensor streamer 106. Stated otherwise, inexample embodiments the forward motion of the tow fish 142 is providedby a force applied to the tow fish 142 from the workboat 140 through theumbilical 144, and thus no propulsion system is needed on the tow fish142. The tow fish 142 moves in a path of travel 302 that is largelyparallel to the path of travel 200 of the survey vessel 102, though aswe shall see the tow fish can be maneuvered to control depth as welllocation in the cross-line directions (i.e., in the view of FIG. 3, thecross-line direction is into and out of the page).

In the example system in FIG. 3, the umbilical 144 is shown coupled tothe derrick 146, and thus the tow force provided to the tow fish 142 byway of the derrick 146. However, in other situations the umbilical 144may couple directly to a spooling device on the workboat 140, and aseparate line may be used to deploy the tow fish into the water and toretrieve the tow fish from the water when the tow fish is at the surfaceof the water. Stated otherwise, while the derrick 146 may be used todeploy the tow fish 142 into the water, and to remove or retrieve thetow fish 142 from the water, the derrick 146 need not necessarily alsoprovide the towing force along the umbilical.

As will be discussed in greater detail below, the tow fish 142 may havea series of control surfaces that enable an operator to maneuver the towfish 142 within the water. In some situations, the operator maneuveringthe tow fish 142 is located on the workboat 140. In other cases, theoperator maneuvering the tow fish 142 is located on the survey vessel102 or some other vessel, and the commands regarding deflection of thecontrol surfaces are sent wirelessly to the workboat 140, as shown byarrows 304, and then relayed to the tow fish 142 by way of the umbilical144. Similarly, video showing the situation in and near the tow fish 142(e.g., as the tow fish 142 lands on the sensor streamer 106) may beconveyed from the tow fish 142 to the workboat 140 over the umbilical144 (and in the situation where the operator resides on the surveyvessel 102, the video signals may be wirelessly transferred).

FIG. 4 shows a side elevation view similar to FIG. 3. In the situationshown in FIG. 4, the tow fish 142 has been maneuvered down to and landedon the sensor streamer 106. That is, in example embodiments a sufficientlength of umbilical 144 is paid out (e.g., two to six times the depth Dof the geophysical streamer 106) to enable the tow fish 142 to maneuverdown to and straddle or land on the sensor streamer 106. It is noted,however, that the payout of the umbilical may be a function of depth ofthe tow fish 142, and thus need not be paid out all at once. Moreover,in some systems the payout of the umbilical may implement heave controlsuch that as the workboat 140 rises and falls on the surface waves, theumbilical 144 is paid out and pulled back to reduce undesirable tuggingon the tow fish 142.

In the landed orientation shown in FIG. 4, the streamer cleaning device300 abuts the sensor streamer 106. Thereafter, based on commands sentalong the umbilical 144, the tow fish 142 latches or closes the streamercleaning device 300 around the sensor streamer 106. Once the streamercleaning device 300 is closed around the sensor streamer 106, based oncommands received across the umbilical 144 the tow fish 142 releases thestreamer cleaning device 300 from various contact points within thepayload area.

FIG. 5 shows a side elevation view similar to FIG. 4. In the situationshown in FIG. 5, however, the tow fish 142 has separated from streamercleaning device 300, and the tow fish 142 is in the process of beingmaneuvered (e.g., by pulling on the umbilical 144 and by operation ofthe control surfaces) back to the surface of the water to be retrievedby the workboat 140. The streamer cleaning device 300 may thus movealong the sensor streamer 106 removing marine growth. Notice that theattaching of the streamer cleaning device 300 in the examples shown tookplace while the sensor streamer 106 was submerged to its operationaldepth D, and while the survey vessel 102 towed the sensor streamer 106through the water along path of travel 200.

At a point later in time than shown in FIG. 5, the streamer cleaningdevice 300 will have made its way to the distal end of the examplesensor streamer 106. The workboat 140 and tow fish 142 of the variousembodiments may then be used to retrieve the streamer cleaning device300 from the sensor streamer 106. In particular, the workboat 140 mayposition itself over the sensor streamer 106 (such as holding positionrelative to the tail buoy 126), with the positioning being dynamic asthe survey vessel 102 continues to tow the sensor streamer 106 duringretrieval in example systems. Thereafter, the tow fish 142 may bedeployed from the derrick 146 and a length of umbilical 144 paid out(e.g., two to four times the depth D of the sensor streamer 106).

FIG. 6 shows a side elevation view after the streamer cleaning device300 has made its way to the distal end of the sensor streamer 106, afterthe workboat 140 has deployed the tow fish 142 into the water, and asthe tow fish 142 is being maneuvered down to retrieve the streamercleaning device 300. In particular, during the retrieval the workboat140 tows the tow fish 142 through the water, while the operatormaneuvers the tow fish 142 down to the streamer cleaning device 300 andsensor streamer 106. Visible in FIG. 6 is the payload area 600.

FIG. 7 shows a side elevation view after the tow fish 142 is landed overthe streamer cleaning device 300 and sensor streamer 106. In some cases,the tow fish 142 is maneuvered such that, once landed, the streamercleaning device 300 is positioned within the payload area 600 of the towfish 142 directly. In other cases (and based on structure discussed morebelow), the tow fish 142 may be landed on the sensor streamer 106proximally of the location of the streamer cleaning device 300, and thetow fish 142 then crabbed distally along the sensor streamer 106 toposition the streamer cleaning device 300 within the payload area 600.

Finally, FIG. 8 shows a side elevation view after the tow fish 142 hascoupled the streamer cleaning device 300 within the payload area, andseparated from the sensor streamer 106 with the streamer cleaning device300 in tow. The operator thus maneuvers the tow fish 142 and streamercleaning device 300 back to the surface, whereupon the derrick 146 mayraise the tow fish 142 and streamer cleaning device 300 out of thewater, possible then to move to the front of the sensor streamer 106, ora different sensor streamer, to re-deploy the streamer cleaning device300.

FIG. 9 shows a perspective view of a streamer cleaning device 300 inaccordance with example embodiments. In particular, the streamercleaning device 300 of FIG. 9 is shown coupled to a sensor streamer 106.The streamer cleaning device 300 is configured to move from a proximalend 900 of the sensor streamer 106 toward a distal end 902, along theway removing marine growth from the sensor streamer 106. Examplestreamer cleaning devices are self-propelled, operating based on energyderived from turbines that turn based on the movement of the sensorstreamer 106 through the water (as towed by the survey vessel 102).Commonly owned U.S. Pat. No. 8,875,722 describes in greater detail aself-propelled cleaner device for sensor streamers, and so as not tounduly complicate the discussion the streamer cleaning device 300, willonly be summarized here.

In particular, visible in FIG. 9 is alignment device 904 coupled toupper frame members 906 and 908. The alignment device 904 is configuredto interact with the wings of streamer position devices, the wingsextending radially outward from a main body coaxial with the sensorstreamer 106 (e.g., streamer positioning devices 132). That is, thealignment device 904 rotationally positions the streamer positioningdevice 132 and/or the streamer cleaning device 300 to enable the wingsto move through the streamer cleaning device 300. As will be discussedin greater detail below, the tow fish 142 (not shown in FIG. 9) couplesto the streamer cleaning device 300 directly or indirectly by way of theupper frame members 906 and 908 interacting with latching mechanisms inthe payload area 600 of the tow fish 142 (neither shown in FIG. 9).

FIG. 10 shows a back elevation view of the streamer cleaning device 300in operational relationship to a sensor streamer 106, with the view ofFIG. 10 looking along the sensor streamer 106 from the distal end towardthe proximal end. In particular, the view of FIG. 10 shows the streamercleaning device 300 closed around the sensor streamer 106. The examplestreamer positioning device 132 of FIG. 10 has three wings 1000transitioning through the streamer cleaning device 300. That is, the twoupper wings 1000 have likely interacted with the alignment device 904 tochange the relative rotational orientation of the streamer positioningdevice 132 and/or the streamer cleaning device 300 such that the upperwings 1000 move through the channels 1002 defined by the upper framemember 906 (and upper frame member 908 (not visible in FIG. 10)). Alsovisible in FIG. 10 are turbines 1004 that rotate based on movement ofthe sensor streamer 106 and streamer cleaning device 300 through thewater. In the example streamer cleaning device 300, the rotation of theturbines 1004 is transferred by way of belts to operate variouscomponents of the streamer cleaning device, such as the cleaning wheels(which physically remove the marine growth) and drive or traction belts(which propel the streamer cleaning device 300 along the sensor streamer106). Thus, the configuration of the streamer cleaning device 300 shownin FIG. 10 relative to the sensor streamer 106 is the configuration thestreamer cleaning device 300 takes when closed around the sensorstreamer 106. However, when landing the tow fish 142 along with thestreamer cleaning device 300 on the sensor streamer 106 to begin acleaning operation, and likewise when separating the tow fish 142 andstreamer cleaning device 300 from the sensor streamer 106 once thecleaning operation is complete, the streamer cleaning device 300 isopened.

FIG. 11 shows an end-elevation view of the streamer cleaning device 300in an open configuration. In particular, in the example streamercleaning device 300 of FIG. 11, the lower components, including theturbines 1004 and cleaning wheels 1100, are coupled to the upper framemember 906 (and upper frame member 908 not visible in FIG. 11) such thatthe various components open or translate away from the location of thesensor streamer to enable the streamer cleaning device 300 to straddlethe sensor streamer. That is, the various components on the left side ofFIG. 11 (e.g., turbine 1004, cleaning wheel 1100, and other variouscomponents) are couple such that the components translate outward (inthe view of FIG. 11, to the left) to create open area 1104 for landingover the sensor streamer. Likewise, the various components on the rightside of FIG. 11 (e.g., turbine 1004, cleaning wheel 1100, and othervarious components) are couple such that the components translateoutward (in the view of FIG. 11, to the right) to create open area 1104for landing over the sensor streamer. An example manner of translatingthe components is discussed in greater detail in commonly owned U.S.Pat. No. 8,875,722 filed Mar. 2, 2011 titled “Self Propelled CleaningDevice for Marine Streamers” (hereby incorporated by reference as ifreproduced in full below). It is noted, however, that any suitablemethod and system may be used to create the open area 1104 for landingover the sensor streamer. Thus, it is the orientation or configurationshown in FIG. 11 in which streamer cleaning device 300 resides both whenthe tow fish 142 is landing on the sensor streamer to place the streamercleaning device 300 at the proximal end of the sensor streamer, and whenthe tow fish 142 is removing the streamer cleaning device 300 from thedistal end of the sensor streamer when the cleaning operation iscomplete. The specification now turns to a configuration of a tow fish142 in accordance with example systems.

FIG. 12 shows a perspective view of a tow fish 142 in accordance withexample embodiments. In particular, FIG. 12 shows that the tow fish hasa frame 1200 that defines a proximal end 1202, a distal end 1204, and alongitudinal or central axis 1206. The example frame 1200 comprises twotubing members 1208 and 1210 that extend parallel to the central axis1206, and two tubing members 1212 and 1214 that are perpendicular to thetubing members 1208 and 1210 (and likewise perpendicular to the centralaxis 1206). Thus, the example tubing members 1208, 1210, 1212, and 1214form a rectangle, and the tubing members themselves are shown as squaretubing, but other frame configurations are possible, includingadditional tubing connections and different tubing cross-sectionalshapes. The example tubing members 1208, 1210, 1212, and 1214 define andreside in a plane. In other cases, the frame may be constructed of astreamlined flat body, and thus the tubing members are not strictlyrequired.

The example tow fish 142 further comprises a first stanchion 1216disposed at the proximal end 1202 of the frame 1200 on a first side ofthe central axis 1206. The first stanchion 1216 extends downward fromthe plane of the frame 1200. The example tow fish 142 further comprisesa second stanchion 1218 disposed at the proximal end 1202 of the frame1200 on a second side of the central axis 1206 opposite the firststanchion 1216. The second stanchion 1218 extends downward from theplane of the frame 1200, and the second stanchion 1218 is parallel tothe first stanchion 1216. The two stanchions 1216 and 1218 define, atleast at the distal tips in example embodiments, cross-sectional shapesin the form of symmetric air foils. In some case, the symmetric air foilshape extends over the entire length of the stanchions. In other cases,and as shown, the inside surfaces (i.e., the surfaces of the stanchionsthat face each other across the central axis 1206) are shaped to form anotch or channel 1220. In particular, the example tow fish 142 furtherdefines a channel 1220 between the stanchions 1216 and 1218, with thechannel 1220 defined below the plane of the frame 1200, the channel 1220parallel to the central axis 1206, and the channel 1220 residing betweenthe distal ends of the stanchions 1216 and 1218 and the plane of theframe 1200. When landing the tow fish 142 onto a sensor streamer 106(not shown in FIG. 12), the channel 1220 is used to guide the tow fish142 in place onto the sensor streamer.

Still referring to FIG. 12, the example tow fish 142 is designed andconstructed to be maneuvered through the water by selective deflectionof plural control surfaces. That is, as the tow fish 142 is pulledthrough the water (based on force provided by the umbilical 144), thecontrol surfaces of the tow fish 142 control yaw of the tow fish (theyaw shown by line 1222), pitch of the tow fish (the pitch shown by line1224), and roll of the tow fish (the roll shown by line 1226). Bycontrolling the yaw, pitch, and roll, the tow fish 142 can be maneuverednot only to control depth, but also to control lateral positioning ofthe tow fish 142 in relation to a sensor streamer (i.e., control thecross-line position of the of tow fish). The commands regardingselective deflection of the control surfaces may be sent along theumbilical 144, which umbilical 144 may comprise not only communicationchannels (e.g., electrical conductors, optical conductors) but alsoropes to provide the towing force for the tow fish 142, and thus theumbilical is a cable as defined above.

In the example system of FIG. 12, the control surfaces are implementedas a plurality of hydrofoils, rudders, and tail flaps. In particular, afirst hydrofoil 1228 extends outward from the first stanchion 1216. Thefirst hydrofoil 1228 has a tapered shape, with the wider portion(measured parallel to the central axis 1206) proximate the stanchion andthe narrow portion distally thereof. Moreover, the first hydrofoil 1228has a swept taper, with the sweep toward the distal end 1204 of theframe. The first hydrofoil 1228 has a rotational axis 1230 about whichthe hydrofoil 1228 is rotated. A second hydrofoil 1232 extends outwardfrom the second stanchion 1218. Like the first hydrofoil 1228, thesecond hydrofoil 1232 has a tapered shape, with the wider portion(measured parallel to the central axis 1206) proximate the stanchion andthe narrow portion distally thereof. Moreover, the second hydrofoil 1232has a swept taper, with the sweep toward the distal end 1204 of theframe. The second hydrofoil 1232 has a rotational axis 1234 about whichthe hydrofoil 1232 is rotated. The example hydrofoils 1228 and 1232 eachhave a cross-sectional shape (vertical cross-section taken parallel tothe central axis 1206) of a symmetric air foil, but othercross-sectional shapes are possible.

The hydrofoils 1228 and 1232 are used to selectively control downwardforce of the tow fish. For example, the hydrofoils 1228 and 1232 arerotated in the same direction about their respective rotational axis1230 and 1234. Rotating both leading edges of the hydrofoils 1228 and1232 up (toward the plane of the frame 1200) causes upward movement. Insome cases the hydrofoils 1228 and 1232 are turned or deflected inunison by equal amounts, and in other cases are turned or deflectedseparately to compensate for roll of the tow fish 142. For example, inthe situation where the tow fish 142 is being maneuvered downward to thesensor streamer, if the leading edge of hydrofoil 1228 is rotateddownward a first amount, and the leading edge of hydrofoil 1232 isrotated downward a second amount less than the first amount, such willprovide a rotational force (e.g., to keep the tow fish 142 level whenwater currents tend to roll the tow fish 142).

Still referring to FIG. 12, the example control surfaces furthercomprise a first tail rudder 1236 disposed at the distal end 1204 of theframe 1200, the first tail rudder 1236 extends upward from the plane ofthe frame 1200, and the first tail rudder 1236 has a rotational axis1238 about which the first tail rudder 1236 rotates. Though someembodiments use only a single tail rudder, the example tow fish 142further comprises a second tail rudder 1240 disposed at the distal endof the frame 1200 on the opposite side of the central axis 1206 from thefirst tail rudder 1236. The second tail rudder extends upward from theplane of the frame 1200, and the second tail rudder 1240 has arotational axis 1242 about which the second tail rudder 1240 rotates. Inthe example system, each of the tail rudders 1236 and 1240 has a taperedshape, being wider at the base (measured parallel to the central axis1206) and narrower at the distal ends thereof. The example tail rudders1236 and 1240 each have a cross-sectional shape (horizontalcross-section taken parallel to the central axis 1206) of a symmetricair foil, but other cross-sectional shapes are possible.

The tail rudders 1236 and 1240 are used to implement yaw control of thetow fish. To control yaw of the tow fish 142, the tail rudders 1236 and1240 are rotated in the same direction about their respective rotationalaxes 1230 and 1234. For example, if both trailing edges of the tailrudders 1236 and 1240 are rotated clockwise (when viewed from above thetow fish 142), the tow fish will tend to yaw in the direction pointed toby the taper of hydrofoil 1228. While in most situations the tailrudders 1236 and 1240 are operated in unison, other situations mayimplement opposite movement. For example, if additional drag is neededat the distal end of the tow fish, the tail rudders 1236 and 1240 may beoperated oppositely (e.g., wherein trailing edge of tail rudder 1236rotates toward the central axis 1206 and the trailing edge of tailrudder 1240 rotates toward the central axis 1206).

The example tow fish 142 further comprises a tail flap 1244 disposed atthe distal end 1204 of the frame 1200. The example tail flap 1244resides between the tail rudders 1236 and 1240, and the tail flap 1244defines a rotational axis 1246 about which the tail flap 1244 rotates.The example tail flap 1244 has a cross-sectional shape (verticalcross-section taken parallel to the central axis 1206) of a symmetricair foil, but other cross-sectional shapes are possible. The tail flap1244 is used to implement, at least in part, pitch control of the towfish. For example, if the tail flap 1244 is rotated such that thetrailing edge moves upward relative the plane of the frame 1200, towfish 142 will tend to pitch nose upward. In the example tow fish shown,the tail flap 1244 resides between the tail rudders 1236 and 1240 and iscoplanar with the plane of the frame 1200 (when the tail flap is in anon-deflected orientation); however, other placements of the tail rudder1244 are possible, such as at the distal ends of the tail rudders 1236and 1240 above the plane of the frame 1200. While it is possible toplace the tail flap 1244 below the plane of the frame 1200, in theexample systems the alignment device 904 of the streamer cleaning device300 extends beyond the distal end of the tow fish 142, and thus havingdevices below the plane of the frame 1200 at the distal end may causeinteraction and/or interference with deploying and retrieving a streamercleaning device 300.

The example tow fish 142 further defines a payload area 600. The payloadarea 600 is defined below the plane of the frame 1200 distal to thestanchions 1216 and 1218. Associated with the payload area 600 is aplurality of latches 1248 (in the example situation, four latches) thatselectively couple to the upper frame members of the streamer cleaningdevice 300. The tow fish 142 further comprises actuators or motors 1250and 1252. The motors are coupled to the frame 1200 at the proximal end1202 thereof, and are disposed distally from the stanchions 1216 and1218. The motors (e.g., electrical, pneumatic) provide a rotationalforce to close the streamer cleaning device 300 around and/or againstthe sensor streamer when the streamer cleaning device is being attachedto the sensor streamer (e.g., FIG. 10). Likewise, the motors provide arotational force to open the streamer cleaning device 300 (e.g., FIG.11) such that the streamer cleaning device 300 can be removed from (andlater attached to) the sensor streamer. The motors 1250 and 1252 aredisposed on opposite sides of the central axis 1206, yet proximate theframe 1200. In particular, motor 1252 is coupled proximate to tubingmember 1208, and motor 1250 is coupled proximate to tubing member 1210.Each motor 1250 and 1252 has a rotor (not specifically numbered in FIG.12), and the rotational axes of the rotors of the motors 1250 and 1252are parallel to the central axis 1206. As implied by FIG. 12 (which doesnot show the streamer cleaning device), motors 1250 and 1252 remaincoupled to and part of the tow fish 142 when the tow fish separates fromthe streamer cleaning device 300.

FIG. 13 shows a perspective view of tow fish 142 attached to a streamercleaning device 300 in accordance with example embodiments. Inparticular, FIG. 13 shows the tow fish 142 having a streamer cleaningdevice 300 coupled within the payload area 600. The streamer cleaningdevice 300 of FIG. 13 is shown in simplified form so as not to undulycomplicate the figure. With streamer cleaning device 300 held within thepayload area 600, latches 1248 couple to the upper frame members 906 and908 of the streamer cleaning device 300. That is, in the example systemsthe latches 1248 hold the streamer cleaning device 300 within thepayload area 600 by way of the upper frame members 906 and 908. Thelatches 1248 may take any suitable form depending on the nature of thestreamer cleaning device 300, and in example systems the latches may bemechanical latches that physically open and close around the upper framemembers 906 and 908, or electromagnetic latches that hold the upperframe members magnetically. In yet still other cases, some or all thelatches may be fixed in position, with latching based on relativeposition of the streamer cleaning device 300 to the frame 1200. Forexample, the back or distal two latches 1248 may be rigid hooks thatcouple to the upper frame member 906 by relative movement (e.g., the towfish and thus the latches move distally to catch the upper frame member906), while the front two latches selectively operated (e.g., physicallyopening and closing, or selectively applying electrical energy to anelectromagnet). As another example, the front or proximal two latches1248 may be rigid hooks that couple to the upper frame member 908 byrelative movement (e.g., the tow fish and thus latches move distally tocatch the upper frame member 908), while the back two latches may beselectively operated (e.g., physically opening and closing, orselectively applying electrical energy to an electromagnet).

Also shown in FIG. 13 is that the motors 1250 and 1252, or at least therotors of the motors (the rotors not specifically shown), interact withcorresponding structure on the streamer cleaning device 300 to selectiveopen and close the streamer cleaning device 300. Moreover, FIG. 13illustrates that, in some embodiments, portions of the streamer cleaningdevice 300 extend beyond the distal end of the tow fish 142, and in theexample system of FIG. 13 the alignment device 904 extends beyond thedistal end of tow fish 142 when the streamer cleaning device 300 islatched within the payload area 600.

FIG. 14 shows a bottom view of the tow fish 142 in accordance withexample embodiments. In particular, visible in FIG. 14 is the frame 1200coupled to the stanchions 1216 and 1218 at the proximal end 1202 of theframe 1200. Extending outward from the stanchions 1216 and 1218 are thehydrofoils 1228 and 1232, respectively. At the distal end 1204 of theframe 1200 are the tail rudders 1236 and 1240, along with the tail flap1244 disposed between the tail rudders 1236 and 1240. Better shown inFIG. 14 are the motors 1250 and 1252 disposed at the proximal end 1202of the frame 1200, and again the motors 1250 and 1252 positioned tointeract with the streamer cleaning device 300 (not shown in FIG. 14)when coupled within the payload area 600. More particularly, rotors 1400and 1402 of the motors 1250 and 1252 interact with mechanical componentsof the streamer cleaning device to open and close the streamer cleaningdevice 300.

FIG. 14 further shows the channel 1220 defined between the stanchions1216 and 1218. Channel 1220 runs parallel to the central axis 1206 ofthe frame member 1200. As discussed above, when landing the tow fish 142onto a sensor streamer, the channel 1220 is abutted against an outsidesurface of the sensor streamer as a means to initially align not onlythe tow fish 142, but also to align the streamer cleaning device 300(not shown in FIG. 14) with respect to the sensor streamer. In somecases, after placing the channel 1220 over the sensor streamer, thesensor streamer is locked within the channel to avoid inadvertentdisassociation of the tow fish 142 from the sensor streamer (andpossibly loss of the streamer cleaning device 300). In example systems,the sensor streamer is locked within the channel by way of a locking bar1404. In particular, locking bar 1404 shown in a deployed orientation orcondition in which the locking bar at least partially spans across thechannel 1220. Thus, when the channel is abutting the outside surface ofthe sensor streamer 106, with the locking bar 1404 in the deployedorientation across the bottom outside surface of the sensor streamer,the sensor streamer cannot be removed from the channel 1220, and thusthe tow fish 142 is locked to the sensor streamer. In a non-deployedorientation, the locking bar 1404 is retracted (retracted position notshown in FIG. 14) such that the locking bar presents no or littleimpediment to entry or exit of the sensor streamer relative to thechannel 1220. Retracting the locking bar 1404 into the non-deployedorientation may take any suitable form. For example, in some cases thelocking bar 1404 physically retracts into one of the stanchions 1216 or1218. In another example embodiment, the locking bar 1404 comprises twolocking components, one of which telescopes within the stanchion 1216,the other of which telescopes within the stanchion 1218. In yet stillother embodiments, the locking bar 1404 is hinged to one of thestanchions, and thus deployment involves rotating the locking bar 1404about the hinge (the axis of rotation parallel to the central axis 1206)to span the channel 1220.

Also visible in FIG. 14 is a portion of a traction belt 1406. Tractionbelt 1406 is disposed within the channel 1220, and the traction beltdefines a contact surface exposed within the channel (i.e., the portionof the traction belt 1406 visible in FIG. 14). In the example systemshown, the traction belt 1406 is disposed at the upper deflection pointof the channel 1220 such that the mass of the tow fish 142 (and downwardforce presented by the hydrofoils 1228 and 1232) tends to press thetrack belt against the sensor streamer. Other locations and numbers oftraction belts are possible (e.g., one traction belt in each stanchionand exposed on the walls of the channel 1220 between the distal ends ofthe stanchions and the apex of channel such that, when a sensor streameris in the channel the traction belts abut or are pressed against the“sides” of the sensor streamer). The traction belt 1406 may be acontinuous belt that turns around pulleys at the proximal end 1408 anddistal end 1410 (the pulleys are within an interior volume of thestructure of the stanchions/channels and thus not visible in FIG. 14).The traction belt 1406 operates similarly to a conveyor belt, exceptrather than conveying objects resting on the belt, the traction belt1406 abuts the outside surface of a sensor streamer within the channel1220, and can move or crab the tow fish 142 (and streamer cleaningdevice if present) along the sensor streamer. That is, the traction belt1406 may move the tow fish toward the proximal end of the sensorstreamer, or may move the tow fish toward the distal end of the sensorstreamer. For example, during operations where the tow fish 142 isretrieving a streamer cleaning device from the distal end of a sensorstreamer after a cleaning operation on the sensor streamer hascompleted, the tow fish 142 may be maneuvered down to the sensorstreamer proximally of the streamer cleaning device. With the sensorstreamer disposed within the channel 1220 (and possibly locked in thechannel by locking bar 1404), the tow fish 142 may crab distally byoperation of the traction belt 1406 to position the tow fish 142 suchthat the streamer cleaning device properly resides within the payloadarea. A similar operation in reverse may be used by the tow fish duringdeployment of the streamer cleaning device onto the sensor streamer atthe proximal end of the sensor streamer. That is, the tow fish 147 mayposition the streamer cleaning device and close the streamer cleaningdevice around the sensor streamer (e.g., by operation of motors 1250 and1252). The tow fish 142 may then crab proximally based on operation ofthe traction belt 1404 to unlatch the streamer cleaning device and/or toclear the streamer cleaning device fully or partially from the payloadarea before retracting the locking bar 1404 and maneuvering away fromthe sensor streamer and streamer cleaning device.

Still referring to FIG. 14, the tow fish 142 further comprises a camera1412 coupled the frame 1200. The camera 1412 has a proximal- orforward-looking field of view that includes the channel 1220. Thus,during operations where the tow fish 142 is being maneuvered onto thesensor streamer, the operator (e.g., on the work vessel 140 or surveyvessel 102) may view channel 1220 and the area in front of and beneaththe channel 1220 to help properly guide the tow fish 142 onto the sensorstreamer 142. The example tow fish further comprises another camera 1414coupled to frame 1200. The camera 1414 has a distal- or rearward-lookingfield of view that includes the payload area 600. Thus, duringoperations where the tow fish 142 is deploying or retrieving thestreamer cleaning device, the operator (e.g., on the work vessel 140 orsurvey vessel 102) may view payload area 600 to help properly guide thetow fish 142 onto or away from the streamer cleaning device 300.

Also visible in the view of FIG. 14 are the various cables used todeflect the tail rudders 1236 and 1240 and tail fin 1244. In particular,deflection rod 1416 emerges from an aperture 1418 in the tubing member1210. The proximal end of the deflection rod 1416 is coupled to anactuator (e.g., a linear actuator) disposed in the internal volumedefined by the stanchions 1216 and 1218. The deflection rod 1416 couplesto the tail rudder 1236 so as to selectively deflect tail rudder 1236.Thus, deflection rod 1416 may carry axial loads in the form of tensionand compression. Similarly, deflection rod 1420 emerges from an aperture1422 in the tubing member 1208. The proximal end of the deflection rod1420 is coupled to an actuator (e.g., a linear actuator) disposed in theinternal volume defined by the stanchions 1216 and 1218. The deflectionrod 1420 couples to the tail rudder 1240 so as to selectively deflecttail rudder 1240. Thus, deflection rod 1420 may carry axial loads in theform of tension and compression. Finally, deflection rod 1424 emergesfrom an aperture 1426 in the tubing member 1210, though the deflectionrod may emerge from any suitable location. The proximal end of thedeflection rod 1424 is coupled to an actuator (e.g., a linear actuator)disposed in the internal volume defined by the stanchions 1216 and 1218.The deflection rod 1424 couples to the tail flap 1244 so as toselectively deflect tail flap 1244.

FIG. 15 shows an electrical block diagram of a control system 1500 inaccordance with example embodiments. In particular, the control system1500 may be disposed in a water-tight compartment within an interiorvolume defined by the stanchions 1216 and 1218, or any other suitablelocation (e.g., in a water-tight compartment above the payload area600). The control system 1500 comprises several subsystems. Eachsubsystem will be addressed in turn, starting with the umbilicalinterface 1502. The umbilical interface 1502 communicatively couples thevarious other subsystems to communication pathways within the umbilical144 (not shown in FIG. 15). For example, the umbilical interface 1502may receive and route package-based messages from the umbilical to anyof the various other subsystems, and may also receive packet-basedmessages from the subsystems and route the messages to the surface overthe umbilical 144. The umbilical interface 1502 may also receive poweracross the umbilical from the surface vessel (e.g., workboat 140), androute the power to the various subsystems.

The control system 1500 further comprises an actuator controller 1504communicatively coupled to the umbilical controller 1502. The actuatorcontroller 1504 operatively couples to devices that control thedeflection of the control surfaces. In the example shown in FIG. 15, theactuator controller 1504 is shown coupled to motors 1506 to illustratecontrol of deflection of the control surfaces; however, the actuatorcontroller 1504 may couple to and control any suitable device or devicesthat can control deflection of the control surfaces (e.g., linear motorscoupled to the deflection rods of the tail rudders and tail flap,stepper motors). The precise electrical makeup of the actuatorcontroller 1504 will depend on the type of actuators controlled, but theactuator controller 1504 may have a processor and memory coupled to theprocessor, the memory storing programs executed by the processor tocontrol deflection of the various control surfaces based on commandsreceived from the operator at the surface across the umbilical.

The control system 1500 further comprises a docking controller 1508communicatively coupled to the umbilical controller 1502. The dockingcontroller 1508 operatively couples to devices that control the latcheswithin the payload area. In the example shown in FIG. 15, dockingcontroller 1508 is shown coupled to solenoids 1510 to illustrate controlof the latches; however, the docking controller 1508 may couple to andcontrol any suitable device or devices that can selectively latch thestreamer cleaning device within the payload area (e.g., linear motors,stepper motors, and electromagnets). The precise electrical makeup ofthe docking controller 1508 depends on the type of latching actuatorscontrolled, but the docking controller 1508 may have a processor andmemory coupled to the processor, the memory storing programs executed bythe processor to control latching based on commands received from theoperator at the surface across the umbilical. Alternatively, thefunctionality of the control may be implemented by other means—forexample, by way of an application-specific integrated circuit (ASIC) orfield-programmable gate array (FPGA) system.

The control system 1500 further comprises a crabbing controller 1512communicatively coupled to the umbilical controller 1502. The crabbingcontroller 1512 operatively couples to the devices that control movementof the traction belt 1406 (and thus control crabbing of the tow fish142). In the example shown in FIG. 15, the crabbing controller 1512 isshown coupled to a motor 1514 to illustrate control of the traction belt1406; however, the crabbing controller 1512 may couple to and controlany suitable device or devices that can control movement of the tractionbelt 1406 (e.g., stepper motors, pneumatic motors, hydraulic motors).The precise electrical makeup of the crabbing controller 1512 depends onthe type of motors controlled, but the crabbing controller 1512 may havea processor and memory coupled to the processor, the memory storingprograms executed by the processor to control movement of the tractionbelt 1406 based on commands received from the operator at the surfaceacross the umbilical.

The control system 1500 further comprises locking controller 1516communicatively coupled to the umbilical controller 1502. The lockingcontroller 1516 operatively couples to devices that control movement ofthe locking bar 1404. In the example shown in FIG. 15, the lockingcontroller 1516 is shown coupled to solenoid 1520 that selective extendsand retracts the locking bar 1404; however, the locking controller 1516may couple to and control any suitable device or devices that canextension and retraction of the locking bar 1404 (e.g., linear motors,stepper motors). The precise electrical makeup of the locking controller1516 depends on the type of actuator controlled, but the lockingcontroller 1516 may have a processor and memory coupled to theprocessor, the memory storing programs executed by the processor tocontrol extension and retraction of the locking bar 1404 based oncommands received from the operator at the surface across the umbilical.

Still referring to FIG. 15, the control system 1500 further comprisescamera controller 1520 communicatively coupled to the umbilicalcontroller 1502. The camera controller 1520 operatively couples tocameras 1412 and 1414, which cameras 1412 and 1414 provide visualizationof the situation near the tow fish 142 during deployment and retrievaloperations. The precise electrical makeup of the camera controller 1520depends on the type of cameras and the communication scheme used tocompress and send the video images to the surface through the umbilicalinterface 1502 and up the umbilical 144. The camera controller 1520 mayhave a processor and memory coupled to the processor, the memory storingprograms executed by the processor to control use of the cameras 1412and 1414.

The control system 1500 further comprises a motor controller 1522communicatively coupled to the umbilical controller 1502. The motorcontroller 1522 operatively to the motors 1250 and 1252 that close andopen and the streamer cleaning device 300 around the sensor streamer.The precise electrical makeup of the motor controller 1522 depends onthe type of motors controlled (e.g., AC motors, DC motors, steppermotors, hydraulic, pneumatic), but the motor controller 1522 may have aprocessor and memory coupled to the processor, the memory storingprograms executed by the processor to control the timing and speed ofoperation of motors 1250 and 1252 based on commands received from theoperator at the surface across the umbilical.

Finally with respect to FIG. 15, the control system 1500 furthercomprises a thrust controller 1524 communicatively coupled to theumbilical controller 1502. The thrust controller 1524 operativelycouples a thrust device 1526 that selectively provides thrust foroperation of the tow fish 142. It is noted, however, that if the thrustdevice 1526 is implemented, the thrust provided is to aid in steeringthe tow device 142 onto or away from the sensor streamer. The force usedto propel the tow fish 142 through the water is largely provided (e.g.,80% or more) by force provided across the umbilical 144. For example,the thrust device 1526 may be used to provide an extra thrust forlateral or cross-line placement of the tow fish 142 during deploymentoperations. The thrust device 1526 may be used to provide an extrathrust for separating the tow fish 142 from the sensor streamer duringretrieval operations. Though not specifically shown on the previousdrawings so as not unduly complicate those drawings, the thrust device1526 may be placed at any suitable location (e.g., associated with thestanchions 1216 and 1218, above or below the plane of the frame. Theprecise electrical makeup of the thrust controller 1524 depends on thedriving mechanism of the thrust devices used (e.g., AC motors, DCmotors, stepper motors, hydraulic, pneumatic), but the thrust controller1527 may have a processor and memory coupled to the processor, thememory storing programs executed by the processor to control the timingand speed of operation of thrust devise(s) 1526 based on commandsreceived from the operator at the surface across the umbilical.

The example control system 1500 of FIG. 15 shows individual controllersfor each sub-system; however, now understanding the tow fish 142 and thecontrol system 1500, with the benefit of this disclosure one of ordinaryskill would recognize that the controllers may be combined in anysuitable fashion (e.g., actuator controller 1504 combined with the motorcontroller 1522 and the thrust controller). Moreover, the functionalityof any of the controllers, alone or in combination, may be implementedby other means—for example, by way of an application-specific integratedcircuit (ASIC) or field-programmable gate array (FPGA) system.

FIG. 16 shows a side-elevation view of a deployment and retrieval methodin accordance with at least some embodiments. In particular, visible inFIG. 16 is the workboat 140 above a sensor streamer 106. Also shown isthe umbilical 144 coupled to the tow fish 142, and the umbilical 144held by the derrick 146. Unlike the previous embodiments where the towfish 142 is maneuvered down to the sensor streamer by way of controlsurfaces, and likewise maneuvered back to the surface by the controlsurfaces, in the example embodiments shown in FIG. 16 the tow fish 142is guided to the sensor streamer 106 by way of guide line 1600. That is,regardless of the whether involved in an initial deployment of thestreamer cleaning device 300, or retrieval of the streamer cleaningdevice 300 after cleaning of the sensor streamer 106 is complete, thefirst step is deployment of a guide line 1600 comprising a hook 1602. Inthe example system of FIG. 16 the guide line also comprises a weight1604 (or other depressor device) that helps pull the distal end of theguide line 1600 deeper than the sensor streamer. In some cases, theweight 1605 and hook 1602 may be the same device. The hook 1602 of theguide line 1600 may then be drawn upward to hook the sensor streamer106. Stated otherwise, the guide line 1600 is coupled between the sensorstreamer 106 and the workboat 140. Once hooked, the guide line 1600 maythen be used to guide the tow fish 142 from the surface to the sensorstreamer by sliding along the guide wire 1600. After the streamercleaning device 300 has been deployed onto (or retrieved from) thesensor streamer 106, the tow fish 142 may be maneuvered back to thesurface, and the guide line 1600 disconnected or released, such as bypaying out additional line to unhook the hook 1602 and having theworkboat 140 move in a cross-line direction prior to spooling in theguide line 1600. The use of the guide line 1600 may reduce or eliminatethe need for some of the control surfaces (e.g., the tail rudders). Andfor the control surfaces that remain the control surfaces may implementsmaller surface area as less overall control may be needed. (e.g., thehydrofoils may be reduced in size).

FIG. 17 is a method in accordance with at least some embodiments. Inparticular, the method starts (block 1700) and comprises transferring astreamer cleaning device to a geophysical sensor streamer (block 1702).The transferring may comprise: towing the geophysical sensor streamerthrough water while the geophysical sensor streamer is submerged (block1704); towing a tow fish through water by way of an umbilical, thestreamer cleaning device coupled within a payload area of the tow fishduring the towing of the tow fish through the water (block 1706);landing the tow fish on the geophysical sensor streamer and therebyabutting the streamer cleaning device against the geophysical sensorstreamer (block 1708); closing the streamer cleaning device around thegeophysical sensor streamer (block 1710); releasing the streamercleaning device from the payload area (block 1712); and separating thetow fish from streamer cleaning device and the geophysical sensorstreamer (block 1714). Thereafter the method may end (block 1716).

FIG. 18 is a method in accordance with at least some embodiments. Inparticular, the method starts (block 1800) and comprises retrieving thestreamer cleaning device from the geophysical sensor streamer (block1802). The retrieving comprises: towing the tow fish through water byway of the umbilical (block 1804); landing the tow fish over thestreamer cleaning device on the geophysical sensor streamer while thesensor streamer is submerged (block 1806); latching the streamercleaning device within the payload area (block 1808); opening thestreamer cleaning device from around the geophysical sensor streamer(block 1810); and separating the tow fish, including the streamercleaning device, from the geophysical sensor streamer (block 1812).Thereafter the method may end (block 1814).

The above discussion is meant to be illustrative of the principles andvarious embodiments of the present invention. Numerous variations andmodifications will become apparent to those skilled in the art once theabove disclosure is fully appreciated. It is intended that the followingclaims be interpreted to embrace all such variations and modifications.

What is claimed is:
 1. A system comprising: a frame that defines aproximal end, a distal end, and a central axis, at least a portion ofthe frame defining and residing in a plane; a first stanchion disposedat the proximal end of the frame on a first side of the central axis,the first stanchion extending downward from the plane of the frame; asecond stanchion disposed at the proximal end of the frame on a secondside of the central axis opposite the first side, the second stanchionextending downward from the plane of the frame; a channel definedbetween the first and second stanchion the channel disposed below theplane of the frame; a first tail rudder disposed at the distal end ofthe frame, the first tail rudder extending upward from the plane of theframe, the first tail rudder having a rotational axis about which thefirst tail rudder is configured to rotate; a tail flap disposed at thedistal end of the frame, the tail flap defining a rotational axis aboutwhich the tail flap is configured to rotate; a payload area definedbelow the frame and distal to the stanchions the payload area configuredto releasable couple to a streamer cleaning device; a locking bar inoperational relationship to the channel, the locking bar having a firstorientation in which the locking bar is retracted and does not block thechannel, and the locking bar having a second orientation in which thelocking bar at least partially spans the channel.
 2. The system of claim1 wherein: the first tail rudder is disposed on the first side of thecentral axis; and a second tail rudder is disposed at the distal end ofthe frame on the second side of the central axis opposite the firstside, the second tail rudder extending upward from the plane of theframe, and the second tail rudder having a rotational axis about whichthe second tail rudder is configured to rotate; and the tail flapextends between the first tail rudder and the second tail rudder.
 3. Thesystem of claim 1 further comprising: a surface vessel; an umbilicalmechanically coupled between the surface vessel and the frame; acommunication controller disposed within the surface vessel, thecommunication controller communicatively coupled to the umbilical on afirst end of the umbilical; and a control system mechanically coupled tothe frame and communicatively coupled to the umbilical on a second endof the umbilical.
 4. The system of claim 1 further comprising: a firsthydrofoil that extends outward from the first stanchion, the firsthydrofoil having a rotational axis about which the first hydrofoil isconfigured to rotate; and a second hydrofoil that extends outward fromthe second stanchion, the second hydrofoil having a rotational axisabout which the second hydrofoil is configured to rotate.
 5. The systemof claim 1 further comprising a control system configured to becommunicatively coupled to an umbilical, the control system comprising alocking controller configured to selectively extend and retract thelocking bar associated with the channel.
 6. A system comprising: a framethat defines a proximal end, a distal end, and a central axis, at leasta portion of the frame defining and residing in a plane; a firststanchion disposed at the proximal end of the frame on a first side ofthe central axis, the first stanchion extending downward from the planeof the frame; a second stanchion disposed at the proximal end of theframe on a second side of the central axis opposite the first side, thesecond stanchion extending downward from the plane of the frame; achannel defined between the first and second stanchion, the channeldisposed below the plane of the frame; a first tail rudder disposed atthe distal end of the frame, the first tail rudder extending upward fromthe lane of the frame, the first tail rudder having a rotational axisabout which the first tail rudder is configured to rotate; a tail flapdisposed at the distal end of the frame, the tail flap defining arotational axis about which the tail flap is configure to rotate; apayload area defined below the frame and distal to the stanchions, thepayload area configured to releasably couple to a streamer cleaningdevice; a traction belt defined within the channel, the traction beltdefining a contact surface exposed within the channel, and the contactsurface configured to at least one selected from the group consistingof: move toward the proximal end of the system; and move toward thedistal end of the system.
 7. The system of claim 6 further comprising acamera coupled to the frame, a field of view of the camera including thechannel.
 8. The system of claim 6 further comprising a camera coupled tothe frame, a field of view of the camera including the payload area. 9.The system of claim 6 further comprising: a first hydrofoil that extendsoutward from the first stanchion, the first hydrofoil having arotational axis about which the first hydrofoil is configured to rotate;and a second hydrofoil that extends outward from the second stanchion,the second hydrofoil having a rotational axis about which the secondhydrofoil is configured to rotate.
 10. The system of claim 6 furthercomprising a control system configured to be communicatively coupled toan umbilical, the control system comprising a crabbing controllerconfigured to control speed and direction of the traction belt.
 11. Asystem comprising: a frame that defines a proximal end, a distal end,and a central axis, at least a portion of the frame defining andresiding in a plane; a first stanchion disposed at the proximal end ofthe frame on a first side of the central axis, the first stanchionextending downward from the plane of the frame; a second stanchiondisposed at the proximal end of the frame on a second side of thecentral axis opposite the first side, the second stanchion extendingdownward from the plane of the frame; a channel defined between thefirst and second stanchion, the channel disposed below the plane of theframe; a first tail rudder disposed at the distal end of the frame, thefirst tail rudder extending ward from the lane of the frame, the firsttail rudder having a rotational axis about which the first tail rudderis configured to rotate; a tail flap disposed at the distal end of theframe, the tail flap defining a rotational axis about which the tailflap is configured to rotate; a payload area defined below the frame anddistal to the stanchions, the payload area configured to releasablycouple to a streamer cleaning device; a traction belt defined within thechannel, the traction belt defining a contact surface exposed within thechannel; a locking bar in operational relationship to the channel, thelocking bar having a first orientation in which the locking bar isretracted and does not block the channel, and the locking bar having asecond orientation in which the locking bar at least partially spans thechannel; a control system configured to be communicatively coupled to anumbilical, the control system comprising: a docking controllerconfigured to selectively control the coupling of latches to thestreamer cleaning device, the latches in the payload area; a crabbingcontroller configured to control speed and direction of the tractionbelt disposed within the channel; a locking controller configured toselectively extend and retract the locking bar associated with thechannel; and a camera controller configured to receive video from adocking camera, and send the video over the umbilical.
 12. The system ofclaim 11 further comprising: a first hydrofoil that extends outward fromthe first stanchion, the first hydrofoil having a rotational axis aboutwhich the first hydrofoil is configured to rotate; and a secondhydrofoil that extends outward from the second stanchion, the secondhydrofoil having a rotational axis about which the second hydrofoil isconfigured to rotate.
 13. The system of claim 12 wherein the controlsystem further comprises an actuator controller configured to controlrotation of the first hydrofoil, the second hydrofoil, the first tailrudder, and the tail flap about their respective rotational axes, theactuator controller responsive to commands received over the umbilical.